The National Aeronautics and Space Administration is beset by problem after problem as it attempts to resume manned shuttle missions in the face of European Space Agency successes and Soviet explorations.

NASA just can't seem to get the Discovery shuttle, on the first post-Challenger mission, out of the testing stage and into flight.With each piece of good news about Discovery's chances of launch in the fall, there has come some bad.

The result is a space agency which is in limbo and losing the confidence of many Americans, including businesses which had counted on the shuttles to carry precious payloads.

Some payloads have gone to the Europeans, whose unmanned rockets not only were able to launch satellites, but ready to do the job.

NASA also faces the usual pressures from the White House. The agency wants to get back into outer space and into the business of space. That is not the problem. Some situations apparently are just outside its control.

The most immediate concern is a leak in a shuttle fuel tank. NASA was alerted to a faulty seal when technicians detected nitrogen tetroxide gas.

Having experienced disaster with one flawed seal, the O-ring in Challenger's solid booster rocket, NASA certainly has reasons to be overly cautious.

It is wise not to seek a "quick fix" to correcting Discovery problems found in Challenger. Discovery is scheduled to launch sometime in the fall.

There is great consolation in knowing that if undetected leaks persist and NASA has done all within its power to make the shuttle as safe as possible, the astronauts may be able to escape catastrophe.

Earlier this month, NASA tested the 1,200-foot "slide for life," an escape safety basket enabling Discovery's crew to evacuate the space craft in the event of an emergency.

The Challenger tragedy gave such important safety devices a higher priority at NASA. In this instance, some good has followed the bad.

NASA is closer to a launch than it has been in the more than two years since the demise of Challenger and crew. That, if little else, is worth cheering about.